For HVAC combustion safety, do not bypass furnace safeties or obstruct venting. If a carbon-monoxide alarm sounds or you smell gas, leave the building and contact emergency services or the gas utility from outside.
Know which HVAC equipment burns fuel
Electric air conditioning does not burn fuel as part of its cooling cycle. A gas furnace does. Do not assume that an alarm is unrelated simply because cooling is running, and do not remain inside to diagnose an alarm source.
Respond to alarms first
If a carbon monoxide alarm sounds or you smell gas, leave the building and contact emergency services or the gas utility from outside. Do not stay inside looking for the HVAC cause.
Refrigerants need qualified handling
The equipment’s refrigerant is not a household maintenance material. Leave leak detection, recovery, charging, and internal circuit work to qualified professionals. Do not mix refrigerants or use an unknown substitute.
Keep systems intact
Do not bypass interlocks, obstruct venting, or alter fuel and electrical connections. Tell the service provider about any recent building or equipment work that could affect the system.
Keep the safety discussion within the HVAC system
A fuel-burning furnace can present combustion and venting concerns; an electric air conditioner does not burn fuel as part of its cooling cycle. Carbon monoxide cannot be reliably detected by smell. A concern in the building should not be dismissed because the central air conditioner itself is electric.
Arrange qualified HVAC care for the furnace, its controls and its venting, and follow the alarm manufacturer’s instructions. During an alarm or suspected gas emergency, leave first and contact emergency services or the utility from outside.
- Identify the exact furnace and fuel type.
- Keep HVAC venting and maintenance records available.
- Report recent building or HVAC exhaust changes to the technician.
- Do not bypass furnace safeties or obstruct HVAC venting.
- Do not use an air cleaner or normal HVAC operation as a response to a CO alarm.
HVAC scope only
This guide addresses furnaces, HVAC electrical equipment, refrigerants and HVAC venting or safety controls. S&S does not present this page as water-heater, household-electrical or generator service. For non-HVAC equipment, contact the properly licensed trade.
General homeowner information from S&S HVAC. Equipment instructions and the approved project scope govern work on your system. Source links support the guidance; they do not imply a manufacturer endorsement.